Your ad can show to a potential customer when your targeted language matches:

• a user’s browser setting
• a user’s Google interface language setting
• the language of websites a user visits most often
• a user’s operating system language

Correct answer is:

• a user’s Google interface language setting

Explanation: Your ads can appear for customers who use Google products and third-party websites in the languages that your campaign targets. This helps ensure that your ads will appear on sites that are written in the language of the customers you’d like to reach.